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Technician Licensing Class

Technician Licensing Class. Antennas. Page 151 to 157. Amateur Radio Technician Class Element 2 Course Presentation. ELEMENT 2 SUB-ELEMENTS (Groupings) About Ham Radio Call Signs Control Mind the Rules Tech Frequencies Your First Radio Going On The Air! Repeaters Emergency!

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Technician Licensing Class

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  1. Technician Licensing Class Antennas Page 151 to 157

  2. Amateur Radio Technician ClassElement 2 Course Presentation ELEMENT 2 SUB-ELEMENTS (Groupings) About Ham Radio Call Signs Control Mind the Rules Tech Frequencies Your First Radio Going On The Air! Repeaters Emergency! Weak Signal Propagation 2

  3. Amateur Radio Technician ClassElement 2 Course Presentation ELEMENT 2 SUB-ELEMENTS (Groupings) Talk to Outer Space! Your Computer Goes Ham Digital! Multi-Mode Radio Excitement Run Some Interference Protection Electrons – Go With the Flow! It’s the Law, per Mr. Ohm! Go Picture These! Antennas Feed Me with Some Good Coax! Safety First! 3

  4. Antennas T9A3 A simple dipole mounted so the conductor is parallel to the Earth's surface is a horizontally polarized antenna. Polarization is referenced to the Earth’s surface Horizontal or Vertical Three element beam Simple Dipole 4

  5. Antennas T9A10 The strongest radiation from a half-wave dipole antenna in free space is broadside to the antenna. T9A9 The approximate length of a 6 meter 1/2-wavelength wire dipole antenna is 112 inches. 468 f (MHz) Length of vertical in feet = _______ 112 inches (for half-wave dipole) Feet = 468/50 = 9.36 9.36 x 12 = 112.3 inches Six Meter ½ Wavelength Dipole 5

  6. Antennas T9A5 You would change a dipole antenna to make it resonant on a higher frequency by making it shorter. T9A2 The electric field of vertical antennas is perpendicular to the Earth. 6 Vertical and Horizontal Polarization H & V Polarized Antennas

  7. Antennas T9A8 The approximate length of a quarter-wavelength vertical antenna for 146 MHz is 19 inches. ______ 234 f (MHz) Length of vertical in feet = (for quarter-wave dipole) (2-meters is 144-148 MHz) Feet = 234/146 = 1.6 1.6 x 12 = 19 inches 19” 7 Radiation Pattern of an Antenna Changes as Height Above Ground is Varied

  8. Antennas T9A6 Directional antennas are the quad, Yagi, and dish. T9A1 A beam antenna concentrates signals in one direction Highest concentration of power Directional Radiation Pattern of a Yagi Beam 8 A Beam Antenna – The Yagi Antenna

  9. Antennas T8C1 Radio direction finding methods are used to locate sources of noise interference or jamming. 9 2-element Yagi DF Antenna 3-element Quad DF Antenna

  10. Antennas T8C2 A directional antenna would be useful for a hidden transmitter hunt. Hidden Transmitter Hunts are called Fox Hunting All ages participate in a Fox Hunt 10

  11. Antennas T3A5 When using a directional antenna, your station might be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path by finding a path that reflects signals to the repeater. Directional Antenna used to bounce signal to reach repeater blocked by building 11

  12. Antennas T9A11 The gain of an antenna is the increase in signal strength in a specified direction when compared to a reference antenna. T3A3Horizontal antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands. Isotropic Radiator Pattern “Gain” of an antenna 12

  13. Antennas T3A4 Signals could be significantly weaker if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization. Transmitter to Receiver – Radio waves from transmitting antennas induce signals in receiving antennas as they pass by 13

  14. Element 2 Technician Class Question Pool Element 2 Technician Class Question Pool Antennas Valid July 1, 2010 Through June 30, 2014

  15. T9A03 Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth's surface? • A ground wave antenna • A horizontally polarized antenna • A rhombic antenna • A vertically polarized antenna

  16. T9A10 In which direction is the radiation strongest from a half-wave dipole antenna in free space? • Equally in all directions • Off the ends of the antenna • Broadside to the antenna • In the direction of the feedline

  17. T9A09 What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna? • 6 • 50 • 112 • 236

  18. T9A05 How would you change a dipole antenna to make it resonant on a higher frequency? • Lengthen it • Insert coils in series with radiating wires • Shorten it • Add capacity hats to the ends of the radiating wires

  19. T9A02 Which of the following is true regarding vertical antennas? • The magnetic field is perpendicular to the Earth • The electric field is perpendicular to the Earth • The phase is inverted • The phase is reversed

  20. T9A08 What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? • 112 • 50 • 19 • 12

  21. T9A06 What type of antennas are the quad, Yagi, and dish? • Non-resonant antennas • Loop antennas • Directional antennas • Isotropic antennas

  22. T9A01 What is a beam antenna? • An antenna built from aluminum I-beams • An omnidirectional antenna invented by Clarence Beam • An antenna that concentrates signals in one direction • An antenna that reverses the phase of received signals

  23. T8C01 Which of the following methods is used to locate sources of noise interference or jamming? • Echolocation • Doppler radar • Radio direction finding • Phase locking

  24. T8C02 Which of these items would be useful for a hidden transmitter hunt? • Calibrated SWR meter • A directional antenna • A calibrated noise bridge • All of these choices are correct

  25. T3A05 When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? • Change from vertical to horizontal polarization • Try to find a path that reflects signals to the repeater • Try the long path • Increase the antenna SWR

  26. T9A11 What is meant by the gain of an antenna? • The additional power that is added to the transmitter power • The additional power that is lost in the antenna when transmitting on a higher frequency • The increase in signal strength in a specified direction when compared to a reference antenna • The increase in impedance on receive or transmit compared to a reference antenna

  27. T3A03 What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? • Right-hand circular • Left-hand circular • Horizontal • Vertical

  28. T3A04 What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization? • The modulation sidebands might become inverted • Signals could be significantly weaker • Signals have an echo effect on voices • Nothing significant will happen

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